Artificial grindstone.



0. SCHMIDT.

ARTIFICIAL GRINDSTONE.

APPLICATION Hum 11u-1o, 1912.

Patented Nov. 12 I1912.

@vih/Leone o :j

UNITED STATES PATENT oEEIcE.

OTTO SCHMIDT, 0F DRESDEN, GERMANY, ASSIGNOB T0 GSEDISCHAFT OTTO SCHMIDTSPATENT HEBGULESSTEINE l. B. I., OI-DEESDEN, GmN'I, .A OURPQRATIGN A0FGERMANY.

Eminem GBINDSTQNE.

Specication of Lette-rs Patent. i Patented-NOV. 12, 1912..

Application led May 10, 1912. Serial No. 686,498. v

more, and as the modern wood-pulp factories commenced the use ofgrinding machines which required considerably greater power, a highlyincreased pressure and augmented velocities, the grind-stones which were.made from the naturalstone did not meet these requirements, and it. wastherefore necessary to make grind-stones from artificial material.Though these artificial grind-stones responded in a greater degree tothe present requirements as to` the capability of resistance than thenatural stone,

they failed in some respects to fully come up to the requirements, andit was therefore 'necessary to improve the same still further.

The object of this invention is to ysupply an artificial grind-stonewhich has all the properties of th`natural stone and in which theexterior portion or ring is made of a mixture of sand and cement and aninterior portion is made of ring-shaped core, said exterior portion andcore being connected by a suitable binding substance interposed betweenthe same.

In theaccompanying drawings, Figure l represents a vertical transversesection d throughfthe improved grind-stone, and Fig..

2 a plan-view of Fig. 1.

Similar letters of reference indicate the same parts in the differentgures of the drawing.

Referring to the drawing, a represents a cylindrical ring which isformed of a mixture of sand and a binding material, such as cement'which corresponds in hardness to the grain of natural sandstone. Thegrinding ring a is reinforced by metallic rings al near its innerportion. The interior ringshaped space inclosed by the cylindricalgrinding ring a is filled up after it has properly hardened with aring-shaped core b of concrete which serves for the reception of theplaster by which the stone is mounted on the shaft, that imparts therotatory motion to the grind-stone. Experience with artificialgrind-stones has shown, however, that by the introduction of theconcrete mass into the grinding ring and the tamping of this mass intothe same, tensions are produced in the ring which exert a weakeningaction on the grinding ring and tend to induce cracks or fissures in thesame. further objection is that the hardening of the concrete which hasbeen tamped into the grinding ring takes up a considerable length oftime so that the artificialgrindstone cannotbe placed into use. Boththese l objections are overcome by making their-ing- The filling thespace 'which is left between the same and the core with suitable bindingsubstance c that is introduced between their adjacent surfaces so'thatan intimate connection of the core with the cylindrical ring is obtainedand both parts form practically one `entire mass. As the interposedbinding material has but little volume, the advantage is obtained thatthe binding and hardening process takes place much quicker, as is thecase with the heavy and thick mass of concrete heretofore used for thecore. Furthermore, the stresses which heretofore have acted unfavorablyon the grinding ring are entirely obviated so that an artificial grindstone is obtained that meets as 'regards stability and permanency themost rigid requirements for such a stone.

Iclaim:

An artiicial'grind-stone for mechanical wood-pulp, comprising anexterior cylinl g l 1,044,261

drical grindin ring, an interior hollow corev of concrete a apted to beplaced on the shaft, and an intermediate layer of a binding substanceinterposed between the grind- 5 ing ring and the lnterior core foruniting the same.

In testimony, that I claim the foregoing as my invention, I have signedmy name in lpresence of two subscribing'witnesses.

OTTO SCHMIDT.

Witnesses ALFRED DIX HEINRICH ARLICH.

